Exercise treadmills are used for various recreational and therapeutic purposes. In these applications, an endless belt typically rotates around two substantially parallel pulleys located at either end of the treadmill. Examples of such treadmills are illustrated in U.S. Pat. Nos. 4,635,928, 4,659,074, 4,664,371, 4,334,676, 4,635,927, 4,643,418, 4,749,181, 4,614,337 and 3,711,812.
In most exercise treadmills, a support deck is located just below the endless belt exercise surface. When a user's foot impacts the exercise surface, the rotating belt presses against the support deck, temporarily causing the belt to rub against the deck. The friction generated between the belt and the deck compromises treadmill performance in several ways. For example, the belt to deck friction reduces belt life and can impede the otherwise smooth movement of the treadmill belt. Furthermore, the additional force required to overcome this friction puts additional stress on and requires additional drive power from the drive system of the treadmill. This in turn leads to an increased electrical power draw from the A.C. main supply. Much of the increased power draw manifests itself as additional heat generated within the treadmill. Additional problems can occur when several treadmills operating from the same A.C. circuit simultaneously require additional power, thereby increasing the current for that circuit beyond the current capacity of the circuit's circuit breaker or other protective device.
Treadmill builders have attempted to minimize the effects of belt to deck friction by waxing either the treadmill deck or the inner belt surface prior to final assembly of the treadmill. For example, some treadmill manufacturers are believed to manually rub a wax bar on the inner belt surface. Other manufacturers are believed to have attempted to embed solid wax particles in the belt itself. Still others are believed to have rubbed wax on the deck, hot waxed the deck, or to have applied some type of non-stick surface to the deck.
Whatever the method, the effects of wax applied during initial assembly of the treadmill apparatus diminishes as treadmill use time increases. While initial belt to deck coefficients of friction are about 0.2, this number increases as treadmill use increases. Eventually, after about 600 hours of use, the effects of increased belt to deck friction cause the belt to deck coefficient of friction to reach the 0.4 range. This in turn requires that the treadmill be serviced in some way to restore it to an operable condition having a serviceably acceptable coefficient of friction of about 0.2 to 0.3.
The servicing of treadmills is a particularly important concern in heavy use applications such as health clubs. In this application, a single treadmill may operate in a nearly continuous manner for eight to twelve hours a day or more. This nearly continuous operation causes a noticeable decrease in performance after 200-300 hours and, if ignored, can lead to treadmill failure after 600-1000 hours. Under these conditions, most club treadmills require service every 3-6 months for about 1/2 to 1 hour. This required servicing is costly and makes equipment unavailable to club patrons during servicing. On the other hand, if preventative treadmill servicing is not performed and the treadmill is allowed to fail, significant damage can occur to the motor, motor control circuits and other components. Repairing this type of failure can require major repair work and result in extensive treadmill service outages. Therefore, to maximize profitability and machine availability, a treadmill apparatus is desired which minimizes belt to deck friction so as to extend the time between rewaxing of or replacement of a belt or deck significantly beyond the average time between service of most treadmill devices.